adding a check (and unit test) that set_meta() must receive name (#111

)

* adding a check (and unit test) that `set_meta()` must receive name

* add to release notes

RELEASE_NOTES.md

@@ -1,6 +1,7 @@
 
 # Next Release
 
+- (#111)[https://github.com/IAMconsortium/pyam/pull/111] extends `set_meta()` such that it requires a name (not None)
 - (#104)[https://github.com/IAMconsortium/pyam/pull/104] fixes a bug with timeseries utils functions, ensures that years are cast as integers
 - (#101)[https://github.com/IAMconsortium/pyam/pull/101] add function `cross_threshold()` to determine years where a timeseries crosses a given threshold
 - (#98)[https://github.com/IAMconsortium/pyam/pull/98] add a module to compute and format summary statistics for timeseries data (wrapper for `pd.describe()`

pyam/core.py

@@ -277,11 +277,12 @@ def set_meta(self, meta, name=None, index=None):
             column to be added to metadata
             (by `['model', 'scenario']` index if possible)
         name: str, optional
-            meta column name (defaults to meta pd.Series.name)
+            meta column name (defaults to meta pd.Series.name);
+            either a meta.name or the name kwarg must be defined
         index: pyam.IamDataFrame, pd.DataFrame or pd.MultiIndex, optional
             index to be used for setting meta column (`['model', 'scenario']`)
         """
-        if not name and not hasattr(meta, 'name'):
+        if (name or (hasattr(meta, 'name') and meta.name)) in [None, False]:
             raise ValueError('Must pass a name or use a named pd.Series')
 
         # check if meta has a valid index and use it for further workflow

tests/test_core.py

@@ -533,6 +533,14 @@ def test_interpolate(test_df):
     assert not test_df.filter(**variable).data.duplicated().any()
 
 
+def test_set_meta_no_name(meta_df):
+    idx = pd.MultiIndex(levels=[['a_scenario'], ['a_model'], ['a_region']],
+                        labels=[[0], [0], [0]],
+                        names=['scenario', 'model', 'region'])
+    s = pd.Series(data=[0.3], index=idx)
+    pytest.raises(ValueError, meta_df.set_meta, s)
+
+
 def test_set_meta_as_named_series(meta_df):
     idx = pd.MultiIndex(levels=[['a_scenario'], ['a_model'], ['a_region']],
                         labels=[[0], [0], [0]],